Method of conditioning polyester textile material and the resulting products



United States Patent METHOD OF CONDITIONING POLYESTER TEX.

TILE MATERIAL AND THE RESULTING PROD- UCTS Julius Hermes, Martinsville,Va., assignor to Martin Processing Company, Incorporated, Martinsvrlle,Va., a corporation of Virginia N0 Drawing. Filed Nov. 9, 1959, Ser. No.851,506

5 Claims. (Cl. 117102) This invention relates to the treatment ofsynthetic textile material of the kind known as Dacron which, as is wellknown in the art, is a condensation polymer of terephthalic acid andethylene glycol, also known as polyethylene terephthalate or, perhapsmore familiarly, as polyester material. More particularly, the inventionrelates to a procedure for conditioning such material whereby it isgiven substantially new and different properties rendering it especiallyadaptable to subsequent processing. The invention also relates to theresulting products, and especially to the undyed products resulting fromthe conditioning treatment. Reference to synthetic textile material orpolyester material hereinafter is to be regarded for the sake of brevityas referring solely to the aforesaid synthetic textile material unlessindicated otherwise by the context.

The method of this invention comprises subjecting the polyester materialto heating at a very high temperature using a hot liquid medium forefiecting the heating. The importance of this type of heating is theliquid or wet, as distinguished from the conventional dry form of heat:ing, such as on drying cans or the like. The liquid heat treatmenteffects an actual impregnation of the polyester textile material withthe hot liquid that imparts to the treated material new properties, eganti-pilling properties, not obtainable by dry heating, and likewisecondi tions the polyester material for more effective additionaltreatments such as, for example, dyeing. This liquid heat treatment orconditioning of the polyester material is preferably carried out withoutsupplemental treatment thereof except for removal or substantial removalof the ice form surface. It appears that the pills or ballsformed' onthe polyester fiber materials do not'break or fall off because of theincreased strength and perhaps other char-, acteristics of these fibersdifferent from the natural fibers.

This polling problem has become acute in view of the fact that thepolyester fiber fabrics and garments of the kind mentioned above exhibitthis undesirable surface etfect after relatively short periods of wearor Washing. In suiting materials, the pilling eifect shows up mainly oncollars, cuffs, sleeves and other portions of the garments that normallyrub against each other or against other surfaces during wear of thegarment, and as a result of this abrasion, even though slight, numerouspills or balls form on the surface. This undesirable effect isespecially noticeable and pronounced in'knitted wear,

heating liquid. Alternatively, this liquid heat treatment may be carriedout first and then followed by additional treatments of the polyestermaterial such as dyeing, since the polyester material is therebyrendered especially amenable to dyeing.

This subsequent treatment of the polyester textile material, however, isnot required and is used only when and as desired to produce someadditional characteristic, such as, for example, dyeing of the material.Independently of dyeing or other subsequent operation, the polyestermaterial treated with the highly heated liquid in accord ance with thepresent invention acquires new physical properties, such as the abovementioned anti-pilling property.

The anti-pilling property is especially important. It has been foundthat fabrics or garments made from the foregoing polyester textilefibers or mixtures thereof with other fibers, when subjected to abrasionsuch as is ordinarily encountered in wearing or laundering, will producepills or small balls of the abraded fibers that do not fall off orbecome separated from the fabric, but adhere to it and produce a veryunattractive surface appearance. This effect is in contrast to theabrasion effects experienced with wool and other natural fibers, and inwhich pills or balls either do not form on the surface of the goods orif they do form they break oft, leaving a smooth uni- 1 such as.sweaters made of Dacron. The numerous pills formed on the surface of thesweaters adhere so tenaciously that they cannot be removed by the usualbI'HSh'.

I have discovered, in accordance with the present in vention, that thisimportant commercial problem can be effectively solved by a heattreatment of these synthetic polyester fiber fabrics with a highlyheated liquid. a result of this heat treatment, the fabric showslittleor no tendency to produce pills or balls even under severeabrasion. In a commercially advantageous example of the process of myinvention, I subject the polyester fiber fabricl'to an impregnationtreatment with a highly heated, non} aqueous, non-evaporative liquidthat quickly heats the polyester textile material to the temperature ofthe liquid and effects rapid penetration thereof by this liquid. Infact, the penetration is sufiiciently deep and uniform that a smallamount of the treating liquid remains imbedded in the fibers of thefabric even after thorough washing and drying of the fabric. This smallresidual impregnant in the fabric aids in identifying the polyestertextile material that has the non-pilling characteristic establishedtherein by treatment of the fabric at a high temperature with the highlyheated liquid in accordance with th present invention, and also confersother desirableprop erties such as those of an internal lubricant'whichenables garment manufacturers more readily and conveniently to processthese fabrics during the garment manufacturing operations. For example,in cutting to pattern numerous layers of stacked polyester fabrics thathave been treated in accordance with the present invention, the residualimpregnant greatly facilitates the cut ting operation by helping to keepthe cutting knife cool. For carrying out the process of my invention, 1have found that it is important to utilize as the highly heated liquidmedium, a liquid having a high boiling point sub: stantially above theboiling point of water, e.g. about 250 F or higher, there being no upperlimit on the boiling point which in practice may run as'high as about550 F. with certain high boilingliquidsfi I Another importantcharacteristic of the liquid tobe used in my process is that it shouldbe non-evaporative, like glycerine and other polyhydric alcohols, asdistinct from the evaporative or vaporizable lower aliphatic alcohols orethers. I 1

A further important aspect of the heated liquid medium used in myinvention is that it should be anhydrous or free of water so as tomaintain the desired high boiling point of the liquid medium and toavoid bubbling and evaporation of the liquid which would otherwise occurin Suitable, but non-limiting, examples of'liquids for -use in myinvention are polyhydroxy compounds such' as ethylene glycol, diethyleneglycol, propylene glycol, dipropylene glycol, butylene glycol andglycerine. 'Of the foregoing, the glycols and glycol ethers orpolyglycols are. preferred. In viewofthe fact that the etfectivenessof'thel highly heated solvent apparently does not. depend upon any ofits chemical properties, but instead uponits physical'properties,particularly the high boiling point.

.therefore easily removable or substantially removable from thepolyester textile material after treatment. Due to,its vsomewhat higherboiling point, and consequently lower vapor pressure at a given elevatedtemperatureof treatment, the dipropylene. glycol ofiers unusuallyattractive properties for'commercial use.

These and similar non-aqueous, non-evaporative high boiling liquidswill, When highly heated, penetrate and impregnate the polyester textilematerial to impart to it anti-pilling or other new and vdesirableproperties and to facilitate subsequent additional treatment such asdyeing'thereof. By using this highly heated liquid for conditioning thepolyester textile material before application of the dyestuff, thefibers of the polyester textile material are made markedly receptive topenetration and impreg nation by the dyestutf. When the polyestertextile inaterial is first conditioned in this, manner, the subsequentdyeing operation can be carried out in a markedly shorter time thanisnormally required. I At the present time it is very difficnlt to dyepolyester materials. have been designed to increase the boiling point ofwater, thus causing the dyestutf to penetrate more readily into thepolyester fibers. This pressure equipment is very costly and is by nomeans the answer to efiicient dyeing procedures. Another method that hasbeen proposed for increasing the dye absorption of the polyestermaterial is dyeing on conventional equipment'using carriers n thedyebath. The most eflective carriers are phenollc compounds. Thesephenols'have several .dis-

Various types of high pressure equipment advantages such as that theyaffect the light fastness adversely, are very difficult to remove fromthe polyester material, and increase the dyeing cost considerably. Anillustration of the dyeing problems encountered when polyester materialsare dyed by conventional methods is thatv one large textile concerncurrently has a fully pressurized dye plant under construction solelyfor the dyeing of polyester materials. The dyeing cycle for polyestermaterials on conventional equipment is approximately 78-14 hours,depending on the depth of shade desired.

The polyester'material conditioned in accordance with the presentinvention may *be dyed very readilyon con.- ventional dyeing equipmentwithout the use of carriers or high pressure equipment. The full dyeingcycle is less than3 hours and complete dyestuff exhaustion is achievedat comparatively low temperatures. It has been found that complete dyeexhaustion takes place at temperatures as low as 180 F.

. Another important characteristic:of the heatedorganic material in asimple manner such as by washing with 1- water, while 'still leaving arelatively small amount entrapped inthe fiber structure;

Further, the liquid heating medium should preferably be neutral incharacter, neither strongly acid nor strongly basic, and otherwisesubstantially inert to the polyester textile material to avoid anyadverse effects when the polyester textile material is impregnated withthe hot liquid.

Regardingtheform of polyester textile material that may be treated inaccordance with the processof my invention, this process has been foundto be applicable to practically any and all forms, such as filaments,staple fibers, threads, yarns andwoven or knitted goods.

The optimum operating temperature for heat treatment of the fabric orother polyester textile material will vary with the particular fiber,and particularly its resistance to heat. For example, when treatingDacron in the form of fabrics, the temperature should not gosubstantially above 365 F. with one kind of Dacron, namely Dacron type64, although with another type of Dacron, namely type 54, a temperatureof about 385 F. is advantageously employed. In general, the organicliquids, used should have a boiling point within the range of about 250F. to 550 F., and preferably about 350 to 550 F.; should not harm thefabric or other polyester material; and should be removable orsubstantially removable therefrom after the heat treatment has beencompleted. I

Where it is desired to effect dyeing subsequently to the wet heattreating process of this invention, practically any and all known typesof dyestuffs suitable for the textile materials undergoing treatment maybe used. These include vats, Indigosols, basic dyes, acid dyes anddispersed dyes, as well as dyestufis more recently developed for dyeingsome of the newer synthetic fibers, such as, for example, Latyl dyes,which are also dispersed dyes.

Regarding the equipment necessary for carrying out this new polyestertextile material conditioning method, it isnot critical in character andis subject to wide variations. The essential requirements are a suitablecontainer for heating the non-aqueous, non-evaporative liquid treatingagent to the desired higher temperatures.

The following are illustrative but non-limiting examples of the processof my invention, in which synthetic polyester fiber textile materialsare treated at high temperatures to prevent or minimizepilling effectsand to impartthereto other improved properties such as better dyereceptivity.

' Example 1 A clean, dry, Dacron fabric is passed through a bath ofdiethylene glycol heated to a'temperature of approximately 360-365 F; Ihave found'that the effectiveness of this'treatment can be obtainedalmost immediately,

that is, with'about ten seconds treatment of the cloth in this highlyheated diethylene glycol bath. After the Dacron fabric passes throughthis liquid bath, the surplus diethylene glycol is squeezed off bysqueeze rolls or the like and the treated cloth is then passed througha-water bath at iordinary room temperature which removes substantiallyall of;the diethylene glycol but leaves a 'very small amount of thediethylene glycol entrapped'in the Dacron fibers. After washing withwater, the polyester fabricis dried and may be used as such or it' maybe'dyedor otherwise finished'as desired. If it is to be 'dyedimmediately following the conditioning step, then of course it need notfirst be dried.

In the event other similar non-aqueous, non-evaporative, water-solubleliquids such as those mentioned above are used for effecting theconditioning treatment, then the procedure described in Examplejlabovewould be gen.-

erally followed with any necessary adjustments of the temperature forthe specific treating liquid, although in 7 general the temperatureswouldbe of the same-high order and sufficient to etfect-atleastafpartial penetration of the polyester textile'fiber fabric with thehighly heated treating liquid, as a result of which the fabric will notthereafter show the usual pilling effect upon abrasion.

Generally speaking, the residual treating liquid retained in and carriedby the polyester textile material, even after washing and drying, willbe relatively small such as of the order of about 2% by weight.

It has been found that the process of my invention may be appliedsatisfactorily, as above described, to cloth or the like consisting of asingle type of Dacron polyester fibers, or composed of a mixture ofDacron and other fabrics, such as, for example, Dacron and wool, etc.,and a subsequent uniform or union dyeing result obtained, assuming ofcourse the proper selection of dyestuff or dyestuifs suited for dyeingthe respective fibers.

Example 2 A number of skeins of Dacron polyester tow were treated asfollows: skeins Nos. 1, 2 and 3 were Dacron type 54 and one-half of eachskein was immersed for 15 seconds in diproplyene glycol at a temperatureof 385 F. Skeins Nos. 4 and were Dacron type 64 and one-half of eachskein was treated for seconds in dipropylene glycol at a temperature of365 F., it being possible to treat the type 64 product at a somewhatlower temperature. a

After treating the Dacron skeins in dipropylene glycol in the foregoingfashion, the treated skeins were chilled in cold water for the purposeof suddenly closing the fiber pores and thereby entrapping relativelysmall traces of dipropylene glycol in the fiber. The skeins were thenwashed in warm water and subjected to dyeing in an otherwiseconventional manner without the use of carrier or high pressureequipment, i.e., in substantially the same manner as in the conventionaldyeing of acetate-rayon. In each case the dyestuff was pasted with asmall amount of Alkanol HCS (du Pont) which acts as a dispersing agentfor the dyestuif.

All dyeings were carried out in an aqueous medium at a temperature of200 F. for a period of one-half hour. The dyestuffs employed were asfollows:

Skein No. 1-Acetamine Rubine B (du Pont) Skein No. 2Eastman Blue BNN(Tennessee-Eastman) Skein No. 3Acetamine Fast Yellow 4 RL (du Pont)Skein No. 4Latyl Brilliant Blue 26 (du Pont) Skein No. 5Sevron Blue 56(du Pont) The first four dyestuffs are dispersed dyestuffs, while thelast dyestuff is a cationic dyestufi.

In all cases the conditioned Dacron (i.e., the half of the skein thathad been immersed in the heated dipropylene glycol) dyed darker and moreevently than non-conditioned Dacron.

The process as described in the specification and defined in the claimsherein for quickly heating the polyester textile material of the kindindicated above with an anhydrous organic liquid at a temperaturebetween approximately 250 and 550 F., but preferably between about 350and 550 F., but below the softening or damaging point for the polyestertextile material, requires a relatively very short time, e.g. less thanabout one minute and usually in the order of eight to fifteen secondstime as specified in the illustrative but non-limiting examples herein.

This application is a continuation-in-part of my prior applicationSerial No. 491,173, filed February 28, 1955, now abandoned, which inturn is a continuation-in-part of my prior application Serial No.415,155, filed March 9, 1954, now abandoned.

The above described materials, conditions and procedures are subject tomodifications and variations, as indicated in the appended claims.

What is claimed is:

l. A process of improving the dyeability and minimizing the pillingeffects in a synthetic polyester textile material comprising acondensation polymer of terephthalic acid and ethylene glycol,comprising the steps of immersing the textile material in a heated,anhydrous, relatively high-boiling, water-soluble, inert, organic liquidmedium in the substantial absence of any dyestuflf and at an elevatedtemperature ofat least 250 F. but below the softening point of thetextile material, for a period of time sufiicient to effect impregnationof the textile material with the heated organic liquid medium and tomodify the fiber structure of the textile material by penetration ofsaid organic liquid medium into said fiber structure but withoutotherwise affecting the fiber structure, removing the textile materialfrom the heated organic liquid medium, and immediately thereaftercontacting the textile material with relatively cool water, therebysubstantially removing the adhering organic liquid medium from thetextile material while leaving entrapped within the fiber structurethereof a small residual amount of said organic liquid medium.

2. A process as defined in claim 1 in which the organic liquid medium isat an elevated temperature of at least 350 F.

3. A product as prepared by the process of claim 1.

4. A process of improving the dyeability and minimizing the pillingefiects in a synthetic polyester textile material comprising acondensation polymer of terephthalic acid and ethylene glycol,comprising the steps of immersing the textile material in a heated,anhydrous, relatively high-boiling, water-soluble, inert, organic liquidmedium consisting essentially of a polyhydric alcohol selected from thegroup consisting of ethylene glycol, di ethylene glycol, propyleneglycol, dipropylene glycol, butylene glycol, and glycerine in thesubstantial absence of any dyestuif, which liquid medium is at anelevated temperature of at least 250 F. but below the softening point ofthe textile material, for a period of time sufficient to effectimpregnation of the textile material with the heated organic liquidmedium and to modify the fiber structure of the textile material bypenetration of said organic liquid medium into said fiber structure butwithout otherwise affecting the fiber structure, removing the textilematerial from the heated organic liquid medium, and immediatelythereafter contacting the textile material with relatively cool water,thereby substantially removing the adhering organic liquid medium fromthe textile material while leaving entrapped within the fiber structurethereof a small residual amount of said organic liquid medium.

5. A process as defined in claim 4 in which the organic liquid medium isat an elevated temperature of at least 350 F.

References Cited in-the file of this patent UNITED STATES PATENTS2,461,612 Olpin et al Feb. 15, 1949 2,537,177 Woodrufi Jan. 8, 19512,663,612 Gibson Dec. 22, 1953 FOREIGN PATENTS 230,891 Switzerland Feb.15, 1944 OTHER REFERENCES American Dyestutf Reporter, Nov. 13, 1950,page 790. 1 lgu Pang Bulletin CSB-D-35, Dacron, July 1954, pages

1. A PROCESS OF IMPROVING THE DYEABILITY AND MINIMIZING THE PILLINGEFFECTS IN A SYNTHETIC POLYESTER TEXTILE MATERIAL COMPRISING ACONDENSATION POLYMER OF TEREPHTHALIC ACID AND ETHYLENE GLYCOL,COMPRISING THE STEPS OF IMMERSING THE TEXTILE MATERIAL IN A HEATED,ANYDROUS, RELATIVELY HIGH-BOILING, WATER-SOLUBLE, INERT, ORGANIC LIQUIDMEDIUM IN THE SUBSTANTIAL ABSENCE OF ANY DYESTUFF AND AT AN ELEVATEDTEMPERATURE OF AT LEAST 250*F. BUT BELOW THE SOFTENING POINT OF THETEXTILE MATERIAL, FOR A PERIOD OF TIME SUFFICIENT TO EFFECT IMPREGNATIONOF THE TEXTILE MATERIAL WITH THE HEATED ORGANIC LIQUID MEDIUM AND TOMODIFY THE FIBER STRUCTURE OF THE TEXTILE MATERIAL BY PENETRATION OFSAID ORGANIC LIQUID MEDIUM INTO SAID FIBER STRUCTURE BUT WITHOUTOTHERWISE AFFECTING THE FIBER STRUCTURE, REMOVING THE TEXTILE MATERIALFROM THE HEATED ORGANIC LIQUID MEDIUM, AND IMMEDIATELY THEREAFTERCONTACTING THE TEXTILE MATERIAL WITH RELATIVELY COOL WATER, THEREBYSUBSTANTIALLY REMOVING THE ADHERING ORGANIC LIQUID MEDIUM FROM THETEXTILE MATERIAL WHILE LEAVING ENTRAPPED WITHIN THE FIBER STRUCTURETHEREOF A SMALL RESIDUAL AMOUNT OF SAID ORGANIC LIQUID MEDIUM.